WASHINGTON/SYDNEY (Reuters) - Delays in identifying satellite images that may show debris of a missing Malaysian plane in the southern Indian Ocean were due to the vast amounts of data that needed to be analysed, Australian authorities and the U.S. company that collected the images said.

Australia rushed four international aircraft to an area about 2,500 km (1,500 miles) southwest of Perth on Thursday after analysis of satellite images identified two large objects that may have come from the Malaysia Airlines plane that went missing almost two weeks ago with 239 people aboard.

DigitalGlobe Inc, a Colorado-based company that collects satellite imagery for the U.S. government and other countries as well as private companies, confirmed it had collected the images on March 16. It did not say when the images were provided to Australian authorities.

Australian Acting Prime Minister Warren Truss said on Friday the Australian Maritime Safety Authority (AMSA), which is leading the search for the Boeing 777 airliner in the southern Indian Ocean, had only received the satellite images on Thursday morning.

However, the data was analysed by Australia's Defence Imagery and Geospatial Organisation (DIGO) before that.

"That was essentially because of the work that was required to essentially identify whether these pictures were relevant, whether the lead was sufficiently promising to shift the search area to that location," Truss told Australian Broadcasting Corp.

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DigitalGlobe spokesman Turner Brinton declined to comment on whether the debris was spotted by the company's own analysts, government analysts or Internet users participating in a "crowdsourcing" effort launched by the company to help locate the plane.

Brinton said more than 6.3 million users were involved in the effort, looking at more than 485 million "map views," which accounted for more than 120,000 sq km of imagery. More than 6.7 million features had been tagged by the crowd, he said.

Australia's Defence Department, which is responsible for DIGO, declined to comment further on Friday on the process and timeline involved in examining the images.

Brinton said the company's five high-resolution satellites capture more than 3 million square km of earth imagery each day.

"This volume of imagery is far too vast to search through in real time without an idea of where to look," Brinton said.

"Given the extraordinary size of the current search area, the lengthy duration of the analysis effort was to be expected," he said in a statement.

Truss said DIGO was continuing to comb through satellite images, even as five aircraft were due to resume the physical search on Friday.

"That work will continue, trying to get more pictures, stronger resolution so that we can be more confident about where the items are, how far they have moved and therefore what efforts should be put into the search effort," Truss said.

The larger of the objects pictured on March 16 measured up to 24 metres (79 feet) long and appeared to be floating in water several thousand meters deep, Australian officials said. The second object was about five metres (16 feet) long.

While describing the images as a credible new lead deserving of the intense physical search underway, Australian and Malaysian authorities have cautioned that the debris in the pictures might not be related to the missing plane.

Still, Steve Wood, a former U.S. intelligence officer who headed DigitalGlobe's analysis unit until July 2013, said the images would allow U.S. and foreign government agencies, and private companies, to launch a more focused search of data gathered by radars, satellites, ships, and other sources at the same time.